Bluetooth® (hereinafter “Bluetooth”), a protocol for wirelessly connecting with a variety of terminals and Bluetooth devices using a frequency in a 2.4-GHz Industrial, Scientific, Medical (ISM) band, automatically or manually discovers (searches) other peripheral Bluetooth devices, if any, and keeps connections. The term “Bluetooth device” as used herein means a device equipped with a Bluetooth module performing Bluetooth communication.
This Bluetooth protocol is applied to all sorts of devices such as, for example, a monitor, a keyboard, a mouse, a wireless headset, a mobile phone, a wireless Local Area Network (LAN) and the like. The Bluetooth protocol may also be used for an information broadcast service that provides various information to Bluetooth devices in the limited space. Examples of the information broadcast service may include advertisement broadcasting in shopping malls, station information broadcasting by public transportation means such as subways and buses, and exhibition broadcasting in exhibition halls.
Generally, a Bluetooth-based information broadcasting scheme can be roughly classified into two types. In a first scheme, when Bluetooth devices that desire to receive information discovers an information providing device that is broadcasting information by continuously performing a discovery process using an inquiry signal, the Bluetooth devices access the information providing device and get (or pull) the information. In a second scheme, when an information providing device discovers a peripheral Bluetooth device by continuously performing a discovery process, the information providing device accesses the discovered Bluetooth device and delivers (or pushes) information to the Bluetooth device. The first scheme consumes excessive power and generates noises in terms of radio spectrum, since all Bluetooth devices should continuously send inquiry response signals. Therefore, the second scheme can be a more common Bluetooth-based information broadcasting scheme.
However, in the latter scheme where the information providing device provides information upon discovering a peripheral Bluetooth device through the inquiry process, the information may be delivered from the Bluetooth information providing device one-sidedly regardless of intention of the discovered Bluetooth device's user. Moreover, a user desiring to receive information may not receive the information.
For example, when an information providing device, serving as a master device, forms a piconet within specific search coverage having a radius of about one hundred meters (100 m) on the basis of a power class ‘1’, the information providing device may establish Asynchronous Connection-Oriented Links (ACL) for data transmission/reception to a maximum of seven slave devices at a time. Therefore, in the case where more than seven peripheral Bluetooth devices exist, even though the time required for delivering (pushing) information is short, a certain Bluetooth device requiring information may not receive the information if the information providing device delivers the information at random.